Extracted from Jonathan Koch, James Strange,Paul Williams.2012. Bumble Bees of the Western United States. A product of the U.S. Forest Service and the Pollinator Partnership
with funding from the National Fish and Wildlife Foundation

Discussion. B. mixtus belongs to the group of species which includes B. edwardsU, melanopygus, sUkensis, and sylvicola. It appears to be most closely (Sarcophagidae) as the principal parasite in nests of B. mixtus.

Description. All castes range from small to medium in body size. Head slightly elongate; malar space square in female, longer than wide in male. Tongue short. Colour pattern as in Figure 11. Some females have black pile on the posterior margins of T2.